Constraint exclusion in partitions

Hi all,

I have split a large table (billions of records) into multiple partitions, hoping the access would be faster. I used an ID to make partitions check (check (id >= 100 AND id < 200)…) and created over 80 tables (children) that are now filled with data.  

However, after I did it, I read a second time the following sentence in the documentation and started wondering what it actually means …

“Constraint exclusion only works when the query's WHERE clause contains constants (or externally supplied parameters)”

It is clear that the following query will use constraint exclusion and will run faster…  

a-      Select * from parent_table where id >=9999; -- using a constant

But how the following queries would react…

b-      Select * from parent_table where id between 2345 and 6789; -- using a range of ids

c-       Select * from parent_table where id in(select ids from anothertable); -- using a list of ids from a select

Since I mostly use queries of type b and c, I am wondering if partitioning the large table was appropriate.

Thank in advance

Daniel

Doc: http://www.postgresql.org/docs/9.3/static/ddl-partitioning.html